Sequence questions

[dddannie6]

Hi,

So I am having trouble understanding how to find the place of a number in a sequence of terms.

Take this question for example:

The first six terms of an infinite sequence are 2,4,4,3,7,5 and these six terms repeat in the same order (e.g., 2,4,4,3,7,5,2,4,4,3,7,5)

Column A
Term 49

Column B
Term 50

Soo....

I am thinking line up the numbers and count the 10th term (because 50 is a multiple of 10) and compare it to the one before it which should be the 49th term. However, this is not really giving me the answer.

According to the explanation if I look to the 6th term and then figure that the 48th term is a multiple of 6 then I will see that this same term will also appear as the 48th term. From there I count the next one which is 49th and then the following, the 50th term, to get the answer as B.

This would be all great if 2 wasn't also a multiple of 48 or 4 or 8 etc... How do I really know what number goes on the 48th term if the number changes depending on how I try to trace it?

What is an absolute way of always getting to the right answer?

Thanks,
D

[tommywallach]

Hey Dannie,

You're counting in sixes because it's a pattern of six. You have to count in sixes. Think of it this way

First Term: 2 --> Seventh Term, 13th, 19, 25, 31, 27, 43, 49
Second Term: 4 --> Eighth Term, 14th, 20, 26, 32, 38, 44, 50
Third Term: 4 --> Ninth Term, etc.
Fourth Term: 3 --> Tenth Term, etc.
Fifth Term: 7 --> Eleventh Term, etc.
Sixth Term: 5 --> Twelfth Term, etc.

See how everything moves in sixes?

-t